(a) Field of the Invention
The present invention relates to a ventilator system, but more particularly, to an improved fan assembly for use in such system and incorporating an adjustable damper to vary the amount of air introduced into the system.
(B) Description of Prior Art
In ventilation systems, it is known to vary the quantity of air circulated therein. There exists the requirement for the provision of a fan that can provide a high degree of control between zero to maximum output effectively for the ventilator system. In the prior art, when no air is required for the system, the motor for the fan is shutoff or the opening at the inlet or outlet of the fan assembly is completely shut. Normally, the opening of such fan housings is provided with shutters which are adjustable to vary the amount of air introduced into the ventilator system. Such controls experience regions of instability thus preventing total control of the fan in the entire range of operation. A further disadvantage of providing such shutters is that these are subject to air pressure and vibration thus causing them to vibrate and create excessive noise and wear of their connecting joints. Still further, these shutters do provide an obstruction to the inlet and outlet of the fan assembly, which obstruction is undesirable. A still further disadvantage is that these shutters are difficult to assemble, require regular maintenance, and result in high electrical consumption of the fan assembly motors. Furthermore, these fans do not provide a high degree of control of the air stream going through the fan assembly.